Power conversion circuits are used in a wide variety of applications. For example, in some applications, a power conversion circuit receives energy from another circuit or from an energy source such as a battery and uses the received energy to provide an output having specified characteristics across a range of conditions. For example, an energy source can supply rectified alternating current or direct current (DC) in a specified voltage range as an input to the power conversion circuit, and an output of the power conversion circuit can include a DC output within a specified output voltage range. Such a power conversion circuit can be referred to as a DC/DC converter.
When a magnitude of the output voltage is larger than a magnitude of input voltage, the converter is referred to as a boost converter. Likewise, when the output voltage magnitude is below the input voltage magnitude, the converter is referred to as a buck converter. Other configurations are possible, such as to provide an output voltage magnitude that can be above or below the magnitude of the input voltage range (e.g., buck/boost or inverting configurations).
DC/DC conversion circuits can also provide regulation of an output parameter (e.g., an output voltage) to constrain the output parameter within a desired range. For example, regulation can be performed using a dissipative element such as a series element or a shunt element. The dissipative element can be controlled by an error signal, such as provided by an amplifier configured to compare information indicative of the regulated output parameter against a reference. Such a closed-loop configuration with a dissipative element can generally be referred to as a “linear” supply configuration because the dissipative element will generally be operated in a “linear” region where the state of the dissipative element varies across of a range of dissipation levels such as proportionally with respect to the error signal, in response to changing conditions such as load current demand, input fluctuation, or temperature, for example.
In another approach, a DC/DC conversion circuit can provide regulation of an output parameter (e.g., voltage), using a switched configuration whereby energy is stored in an intermediate energy storage element during a first interval, and the energy is then transferred to a load during a second interval, using one or more series or shunt switching devices configured to operate in a highly-conducting mode (e.g., a saturated or switched-on state) or in a non-conducting mode (e.g., a cut-off or blocking state). The energy storage element can include one or more of a capacitor or an inductor. Regulation can be achieved in switched-mode DC/DC converters, such as in response to feedback by varying one or more of a pulse width or a pulse frequency of signals used to control switching elements in the switched-mode converter, or using other techniques.